Morphological studies of pollen grains of the Polish endemic species of the genus Rubus (Rosaceae)

Abstract

The pollen of six taxa of the genus Rubus endemic to Poland (R. capitulatus, R. chaerophylloides, R. ostroviensis, R. posnaniensis, R. seebergensis and R. spribillei)was studied using light and scanning electron microscopy. The study objective was to extend the knowledge of the species pollen morphology and to investigate whether pollen morphology may help to taxonomically distinguish a very rare bramble species. Study material was derived from six natural localities where the species occur in the Wielkopolska region (Poland). Ten quantitative pollen grain features were analysed as well as the following qualitative ones: outline, shape, type of bridge and exine sculpture. Only mature, correctly formed pollen grains (30 per specimen) were measured and 180 pollen grains were examined in total. It was found that R. capitulatus and R. seebergensis had the highest mean values of P, E and Le features. In addition, pollen grains of R. capitulatus were most flattened (mean P/E ratio equals 1.14), while those of R. seebergensis were most elongated (mean P/E ratio equals 1.27). R. spribillei was the only species with striae of similar width as muri, whereas striae in the remaining species were wider. R. chaerophylloides and R. posnaniensis were characterised by specific, similar exine sculpture. Nevertheless, it should be stated that differences between pollen features of the species studied are so small and the variability of these features are so large that it is difficult to clearly identify the species studied. Therefore, pollen grain morphology can serve only as an auxiliary feature for the determination of these species.

Comparison of pollen grain morphological features of selected species of the genusCrataegus(Rosaceae) and their spontaneous hybrids

“…Extensive research on the range of pollen grain variation of several species of Rosa L., at the inter‐ and intraspecific levels, and on flower variation, at the individual and population levels, were conducted by Wrońska‐Pilarek & Jagodziński (, ). There are a few other published studies in which coefficients of variation of selected pollen grain morphological traits have been analysed for the taxa of Rubus L. and Spiraea L. (Naruhashi & Takano, ; Polyakova & Gataulina, ; Wrońska‐Pilarek, Jagodziński & Maliński, ).…”

Combined LM and SEM study of the middle Miocene (Sarmatian) palynoflora from the Lavanttal Basin, Austria: part IV. Magnoliophyta 2 – Fagales to Rosales

“…The basic pollen morphology of all three rosaceous subfamilies (see Potter et al 2007) and many genera/species of the tribes and subtribes within Rosaceae have been studied to some extent. Pollen types of the subfamily Rosoideae have been studied using mostly LM and SEM by Huang (1972), Hebda et al (1988aHebda et al ( , 1988b, Hebda and Chinnappa (1990), Jones et al (1995), Wang et al (1995), Beug (2004), Tahir (2005), Fujiki and Ozawa (2007), Chung et al (2010), Li et al (2011a), Miyoshi et al (2011), Wrońska-Pilarek (2011), Wrońska-Pilarek and Jagodziński (2011), Wrońska-Pilarek et al (2012, Perveen and Qaiser (2014) and Faghir et al (2015). The subfamily Dryadoideae has been studied by Hebda et al (1988b) and Beug (2004).…”

Pollen morphology of Polish species from the genusRubusL. (Rosaceae) and its systematic importance

“…Similarly to a majority of palynologists, the authors of this study maintain that exine ornamentation features were diagnostic for pollen grains of the Rubus species [25–28, 30–32, 35, 39, 40, 42, 43, 58, 59]. The most important exine ornamentation traits include the width, number and course of grooves (muri) and the width of the striae as well as the number and diameter of perforations [31, 32, 35, 42, 43, 59–61]. Some authors considered pollen size and shape as potentially important features in the diagnosis of the analysed genus [30, 32, 58], while others claim that they have no diagnostic significance [31, 42, 44].…”

“…As a result, pollen grains of only 48 European bramble species have been described [24–34]. Among the 108 Polish brambles species, pollen of just 15 species has been characterised so far, of which six are endemic species [31, 32, 35].…”

“…The most important characteristics of bramble pollen grains include exine ornamentation (ornamentation type, width and orientation of striae and grooves), lenght of colpori, type of the bridge (clamped vs. stretched), costae colpi and the number and size of perforations [25–32, 34–48]. According to Tomlik-Wyremblewska [31, 42], pollen size and shape prove to be poor criteria in species identification.…”